For Pcomp this week I used an analog raindrop sensor board to simulate rainfall in p5. The sensor "senses rain" when water shorts the connections running throughout the board.
I adapted some code Daniel Shiffman wrote for a purple rain sketch to create the rain effect when p5 reads the sensor value in via serial. This was my first time using p5 and I found it super easy to use, if not a little basic (seems a lot easier to get started with than something like d3).